Children with cancer experience stress/trauma during certain treatment-related procedures (e.g.,lumbar punctures, bone marrow aspirations). Negative behavioral/psychological reactions to treatments may make the child a more difficult patient and may place the child at greater risk for psychosocial disorders and possibly even maltreatment (Bugental, 2000). Adverse reactions to cancer-related treatments may thus seriously affect the long-term survivorship and quality of life of the pediatric cancer patient. The goal of this study is to determine the influence of the following variables on differences in children's reactions to painful treatments: prior medical history, personal attributes of the child, personal attributes of the child's primary adult caretaker, the nature of the child-caretaker relationship, and the adult's thoughts, feelings, and actions immediately prior to and during an actual treatment session. The study aims are: 1) to identify the personal attributes of children, personal attributes of their adult caretakers, and the adult-child interaction patterns that covary with the child's affective and behavioral reactions to invasive and painful cancer treatments; 2) to examine the extent to which a child's affective and behavioral reactions to a treatment covary with post-treatment psychosocial and health status, and other factors related to long-term survival; and 3)to conduct a preliminary test of significant portions of a multilevel model of the relationships between the hypothesized causes of children's affective and behavioral reactions to painful treatments and the psychosocial, behavioral, and medical consequences of these reactions. One-hundred thirty-five children undergoing lumbar puncture/bone marrow aspirations and their primary caretaker will be recruited for the study. Interviews will be conducted with the children and parents in the home several days prior to the procedure to collect self-report data and physiological data related to general reactions to stressors. Next, the child-parent-staff interaction will be videotaped during the child's procedure. Additionally, child/parent saliva samples for cortisol level will be used to measures stress, and unused spinal fluid drawn from the child during treatment will be analyzed for brain chemical activation related to mood, emotion, arousal, attention, and stress. Finally, psychosocial and health status will be assessed several days after treatment procedure.